To intensify the dusting, I applied various mixes of pigment with a dry brush. Next, I soaked the area with thinner from MIG or turpentine. Once that dried, I worked with brush, fingers and cotton tips to remove some of the pigment in those areas where I didn't want as much.

This step took me quite long I have to say as I went back and forth between applying dry pigment and washing thinner over it and rubbing / correcting with a brush once dry again.

In a few spots where I wanted it to look like dust really settled heavily in crevices, I mixed pigment with thinner and applied that as a very targeted wash (i.e., the little hatches on top of the front part of the truck). Again, it took me a few attempts to get a feel for the right pigment / thinner ratio, to get it right.